Normal Operation - Vehicles equipped with a CDIM

The ignition switch and the CDIM work together to distribute fused battery voltage to the BCM internal logic, PCM and BSIA. When the ignition switch is placed in the ACC position, the CDIM is in a passive state allowing the voltage to pass through the module using normally closed relays. When the ignition switch is placed in the RUN position the CDIM becomes active. While active, the CDIM allows ignition voltage to pass through the internal relays, but it also monitors the Medium Speed Controller Area Network (MS-CAN) for messages. Voltage is supplied to the BCM through the CDIM, when the ignition switch is placed in the ACC, RUN and START positions.

This pinpoint test is intended to diagnose the following: 

• Fuse(s)
• Wiring, terminals or connectors
• Ignition switch
• BCM